Humans can recognize a familiar object even though it dramatically changes appearance as it is viewed from different angles, distances, and lighting conditions. The aim of the proposed research is to use fMRI to directly examine object representations in visual cortex that support invariant object recognition in humans. Changes in neural activity will be measured with respect to several object transformations such as changes in object size, orientation, and illumination direction. Most importantly, the degree of change will be varied parametrically in order to describe the neural tuning (i.e., sensitivity) of each area to a particular transformation. Unlike previous studies, this methodology provides for a precise determination of the degree to which a visual area is invariant to a particular transformation. In addition, changes in the neural tuning functions when participants attend to a transformation compared to when they do not, will reveal both the degree and manner of top-down modulation. Taken together, these findings would provide for a comprehensive understanding of the function and organization of visual cortical areas involved in invariant object recognition. In addition, the findings would be of critical importance for understanding the impact of neurological damage depending upon the representations within the underlying cortical area.